U.S. patent application number 10/515650 was filed with the patent office on 2006-03-09 for battery.
Invention is credited to Tetsuzo Kojima, Takehito Matsubara, Noriyoshi Munenaga, Takeshi Shimozono, Isao Suzuki, Hiroshi Tasai.
Application Number | 20060051664 10/515650 |
Document ID | / |
Family ID | 29585978 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060051664 |
Kind Code |
A1 |
Tasai; Hiroshi ; et
al. |
March 9, 2006 |
Battery
Abstract
The metal foil of the positive electrode 1a or the negative
electrode 1b in the power generating element 1 is connected along
the connecting plate portion 2b which is folded, twisted, and
provided in a protruding condition from the main portion 2a of the
current-collector connector 2; hence the shape of the
current-collector connector 2 becomes easy to form, and a battery
capable of enhancing current collection efficiency, reliability and
workability can be provided.
Inventors: |
Tasai; Hiroshi; (Kyoto,
JP) ; Suzuki; Isao; (Kyoto, JP) ; Shimozono;
Takeshi; (Kyoto, JP) ; Munenaga; Noriyoshi;
(Kyoto, JP) ; Kojima; Tetsuzo; (Kyoto, JP)
; Matsubara; Takehito; (Kyoto, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Family ID: |
29585978 |
Appl. No.: |
10/515650 |
Filed: |
May 27, 2003 |
PCT Filed: |
May 27, 2003 |
PCT NO: |
PCT/JP03/06589 |
371 Date: |
June 13, 2005 |
Current U.S.
Class: |
429/161 ;
429/180; 429/211 |
Current CPC
Class: |
Y02E 60/10 20130101;
H01M 50/54 20210101; H01M 10/052 20130101; H01M 10/0587
20130101 |
Class at
Publication: |
429/161 ;
429/211; 429/180 |
International
Class: |
H01M 2/26 20060101
H01M002/26; H01M 2/06 20060101 H01M002/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 27, 2002 |
JP |
2002-151808 |
May 30, 2002 |
JP |
2002-156704 |
Claims
1. A battery comprising a battery case, a power generating element
being configured by overlapping a positive electrode and a negative
electrode with an isolation material therebetween, and a
current-collector connector being electrically connected to said
positive electrode or said negative electrode in said power
generating element, wherein said current-collector connector
comprises of a plate-like main portion and a plurality of
connecting plate portions which are provided at said main portion
so as to be at approximately 90 degrees to said main portion, and
said connecting plate portions are disposed along the electrode
faces at the end of said power generating element and electrically
connected to said positive electrode or said negative
electrode.
2. The battery according to claim 1, wherein the shape of said main
portion of said current-collector connector is approximately
trapezoidal, an external connection terminal is provided at the
section near the short side of said main portion, and said
connecting plate portions are provided at the long side of said
main portion.
3. The battery according to claim 1, wherein a pinching plate which
holds one of said connecting plate portions of said
current-collector connector and said positive electrode or said
negative electrode which is connected to said one of said
connecting plate portions is provided in said battery.
4. The battery according to claim 1, wherein protruding convex
portions are formed on the surface of at least one of said
connecting plate portions of said current-collector connector so as
to face said positive electrode or said negative electrode which is
connected to said one of said connecting plate portions.
5. The battery according to claim 3, wherein said power generating
element is configured by winding positive and negative electrodes
and a separator, and the cross section of said power generating
element perpendicular to the winding axis forms an elliptic
cylindrical shape having a linear part, and the length of said
pinching plate is shorter than that of said linear part of said
power generating element.
6. A battery according to claim 5, wherein a pair of said
connecting plate portions is present per said power generating
element, and said pinching plate is present per connecting plate
portion, and said pair of said connecting plate portions is
disposed so as to hold the end portion of said power generating
element from the outside, and said pinching plate is disposed so as
to lie at the outside of said one of said connecting plate portion
and at the center of the winding of said power generating
element.
7. A battery according to claim 1, comprising an external
connection terminal which is placed on said battery case, wherein
said external connection terminal is connected to said
current-collector connector.
8. A battery according to claim 7, comprising a battery terminal
which is set on the exterior of said battery case, and a terminal
connection member which is disposed on the exterior of said battery
case and connected and fixed to the outward protruding portion of
said battery terminal, wherein said external connection terminal is
connected to said battery terminal through said terminal connection
member.
9. A battery according to claim 2, wherein a hole into which said
external connection terminal is inserted is formed at the section
near said short side of the approximately trapezoidal shape of said
current-collector connector main portion, and one end of said
external connection terminal is connected and fixed to said hole,
into which said external connection terminal is inserted, in the
inside of said battery case, and the other end of said external
connection terminal is derived to the outside of said battery
case.
10. A battery according to claim 9, wherein when the distance from
the center of said short side to the center of said hole is
referred to as D and the diameter of said hole is referred to as R,
R is not less than 0.5 D.
11. A battery comprising a battery case, power generating elements
and current-collector connector, wherein each of said power
generating elements is configured by overlapping a positive
electrode and a negative electrode with an isolation material
therebetween, said current-collector connector is electrically
connected to said positive electrodes or said negative electrodes
in said power generating elements, said current-collector connector
comprises a plate-like main portion and a plurality of connecting
plate portions which are provided at said main portion so as to be
at approximately 90 degrees to said main portion, and said
connecting plate portions are disposed along the electrode faces at
the ends of said power generating elements and electrically
connected to said positive electrodes or said negative
electrodes.
12. The battery according to claim 11, wherein the shape of said
main portion of said current-collector connector is approximately
trapezoidal, an external connection terminal is provided at the
section near the short side of main portion, and said connecting
plate portions are provided at the long side of said main
portion.
13. The battery according to claim 11, wherein a pinching plate
which holds one of said connecting plate portions of said
current-collector connector and said positive electrode or said
negative electrode which is connected to said one of said
connecting plate portions is provided in said battery.
14. The battery according to claim 11, wherein protruding convex
portions are formed on the surface of at least one of said
connecting plate portions of said current-collector connector so as
to face said positive electrode or said negative electrode which is
connected to said one of said connecting plate portions.
15. The battery according to claim 13, wherein one of said power
generating elements is configured by winding positive and negative
electrodes and a separator, and the cross section of said one of
said power generating elements perpendicular to the winding axis
forms an elliptic cylindrical shape having a linear part, and the
length of said pinching plate is shorter than that of said linear
part.
16. A battery according to claim 15, wherein a pair of said
connecting plate portions is present per said power generating
element, and said pinching plate is present per connecting plate
portion, and said pair of said connecting plate portions is
disposed so as to hold the end portion of said power generating
element from the outside, and said pinching plate is disposed so as
to lie at the outside of said one of said connecting plate portions
and at the center of the winding of said power generating
element.
17. A battery according to claim 11, comprising an external
connection terminal which is placed on said battery case, wherein
said external connection terminal is connected to said
current-collector connector.
18. A battery according to claim 17, comprising a battery terminal
which is set on the exterior of said battery case, and a terminal
connection member which is disposed on the exterior of said battery
case and connected and fixed to the outward protruding portion of
said battery terminal, wherein said external connection terminal is
connected to said battery terminal through said terminal connection
member.
19. A battery according to claim 12, wherein a hole into which said
external connection terminal is inserted is formed at the section
near said short side of the approximately trapezoidal shape of said
current-collector connector main portion, and one end of said
external connection terminal is connected and fixed to said hole,
into which said external connection terminal is inserted, in the
inside of said battery case, and the other end of said external
connection terminal is derived to the outside of said battery
case.
20. A battery according to claim 19, wherein i when the distance
from the center of said short side to the center of said hole is
referred to as D and the diameter of said hole is referred to as R,
R is not less than 0.5 D.
Description
TECHNICAL FIELD
[0001] The present invention relates to a battery having
characteristics in current-collection structure.
BACKGROUND ART
[0002] FIG. 9 shows the conventional connection structure of power
generating elements 1, current-collector connectors 2, and external
connection terminals 3 in a non-aqueous electrolyte secondary
battery. In this non-aqueous electrolyte secondary battery, two
power generating elements 1 of an elliptic cylindrical shape are
connected in parallel.
[0003] Each power generating element 1 such as shown in FIG. 3 is
configured by winding a positive electrode 1a and a negative
electrode 1b with a separator 1c therebetween into an elliptic
cylindrical shape. In the positive electrode 1a, the surface of a
strip aluminum foil 1d to be used as an electrode substrate is
supported with a positive active material; and in the negative
electrode 1b, the surface of a strip copper foil 1e to be used as
an electrode substrate is supported with a negative active
material. These positive electrode 1a and negative electrode 1b are
provided with non-coated portions, where the active material is not
applied to one side-edge portions of the negative strip and to the
other side-edge portions of the positive strip, thereby allowing
the aluminum foil 1d and the copper foil 1e to be exposed in the
non-coated portions. And, in the formation of the power generating
element 1 by winding, these positive electrode 1a and negative
electrode 1b are wound with being shifted in the opposite direction
from each other along the winding axis, so that only the aluminum
foil 1d at the side-edge portions of the positive electrode 1a
protrudes from one end face of the elliptic cylindrical shape and
only the copper foil 1e at the side-edge portions of the negative
electrode 1b protrudes from the other end face.
[0004] The above-described two power generating elements 1, 1 are
aligned horizontally so that the flat side of each elliptic
cylindrical shape overlaps each other in an upright stance. And, at
both sides of the end faces of these power generating elements 1,
1, each electrode is connected to the current-collector connectors
2, 2 of a ribbed plate type, respectively. The aluminum foil of the
positive electrode 1a or the copper foil of the negative electrode
1b protruding from the end face of the power generating element 1
is held in each of the concave portions of a ribbed plate type,
ultrasonic welding is performed, and hence, the electrodes are
connected and fixed.
[0005] However, there arose a problem in that the use of the
above-described structure made it difficult for the
current-collector connector to be connected to the power generating
element. Moreover, in case of a battery having a large capacity, it
is necessary to make a plate thickness of the current-collector
connector 2 thick enough for a large amount of electric currents to
pass, thereby causing another problem of easy occurrence of
defective welding when ultrasonic welding was performed on the thin
aluminum foil or copper foil which was held in it.
DISCLOSURE OF THE INVENTION
[0006] It is an object of the present invention to solve these
problems and provide a battery having the current-collector
connection structure of easy working and high reliability.
[0007] The battery of the present invention comprises a battery
case, power generating elements being configured by overlapping
positive and negative electrodes with an isolation material such as
a separator therebetween, and current-collector connectors being
electrically connected to said each electrode in said power
generating elements, respectively, wherein said current-collector
connectors consist of a plate-like main portion and a plurality of
connecting plate portions which are provided at the edge of the
main portion so as to be at approximately 90 degrees to the main
portion, and said connecting plate portions are disposed along the
electrode faces at the ends of said power generating elements and
electrically connected to said electrodes.
[0008] In this battery, the connection of the current collectors is
made by means of the connection between the connecting plate
portions and the electrodes; hence, the connection work is
implemented easily.
[0009] The above-described connecting plate portions are formed in
such a manner that one edge portion of a metal plate is cut into
predetermined dimensions and, diverging from the main portion, the
cut portions are folded downward and twisted at approximately 90
degrees so as to be able to be set along the electrode faces of
said power generating elements; hence, by using a current-collector
connecting plate of a simple structure which is made, for example,
only by punching, folding, and twisting a metal plate, it becomes
possible to perform effective current collection at a low
price.
[0010] Moreover, with a twist angle being made approximately 90
degrees, it becomes possible to connect the connection faces of the
electrodes along the plate faces of the connecting plate portions;
hence, the connection can be made secured.
[0011] In addition, it is desirable that the above-described
connecting plate portions be provided in one or more pairs, and
that by diverging from the metal potion which composes the main
portion and by being twisted in the opposite direction from each
other, the sides of each pair of two connecting plate portions be
made to face each other. With the connecting plate portions being
provided in pairs, the electrode which protrudes from the end face
of the power generating element is inserted between the two
connecting plate portions and the connection work is carried out,
thereby allowing the connection work to be easy. In addition,
twisting the connecting plate portions in the opposite direction
from each other makes it easy to insert the electrode between them,
so that the work of fixing the current-collector connecting plate
to the power generating element becomes easier.
[0012] When connecting plate portions are twisted, it is desirable
that the length of the twisted portions in the protruding direction
of the connecting plate portions be longer than the thickness of
the plate of the connecting plate portions. When precipitous
twisting is applied for a short period of time, stress is
concentrated on the twisted portions of the connecting plate
portions, electronic conductivity deteriorates, and the internal
resistance of the battery could become high; however, the above
consideration can prevent this from occurring.
[0013] In addition, it is preferable that protruding convex
portions be formed on the surface of the connecting plate portion
of the above-described current-collector connector so as to face
the above-described electrode in the above-described power
generating element. The formation of the convex portions allows the
welding or crimping of the electrode substrates to be centralized
on these convex portions, so that it becomes possible to connect
and fix them more firmly.
[0014] In addition, it is more preferable to be equipped with
pinching plates which hold the connecting plate portion of the
above-described current-collector connector and the electrode which
is connected to this portion. The connection portion of the
current-collector connector is overlapped with the electrode
substrates of the electrode in the power generating element, such
overlapped part is held in a pinching plate, and welding or the
like can be performed; therefore, it is possible to increase the
section area of this connection portion so that large amounts of
current can pass, and for use as a pinching plate it is possible to
use a metal plate having an adequate thickness for welding or
crimping. Hence, by the use of a thin pinching plate most suitable
for ultrasonic welding and the like, the electrode substrates can
be firmly welded to the connection portion of the current-collector
connector, and connected and fixed; so that there is no fear of the
break of these electrode substrates. In addition, on the contrary,
if the thickness of a pinching plate is made sufficiently thick, by
applying firm pressure on this pinching plate from the outside, it
becomes also possible to firmly crimp the electrode substrates and
the connection portion of the current-collector connector, and then
connect and fix them. Moreover, the electrode substrates can be
held with every connection portion of the current-collector
connector by means of a pinching plate; therefore, the assembly
work becomes easy, too.
[0015] The shape of the main portion of the above-described
current-collector connector is approximately trapezoidal and,
concerning the structure, it is more preferable that an external
connection terminal be provided at the short side and connecting
plate portions at the long side.
[0016] The flow of electricity from a power generating element to
an external connection terminal passes through the shortest
distance from a connection portion to the external connection
terminal; hence, the triangular edge portions 2c locating at both
sides of the terminal insertion hole 10 of the current-collector
connector, as shown in FIG. 5, not only fail to serve a function as
current collectors, but also increase the battery weight and
deteriorate the weight energy density due to their own existence.
In contrast to this, the use of an approximately trapezoidal shape
allows a section unnecessary for the current-collection function of
the current-collector connector to be cut off, so that a battery
having a high weight energy density can be provided without losing
the current-collection function.
[0017] When the above-described power generating elements are
configured by winding positive and negative electrodes with a
separator, and the cross section perpendicular to the winding axis
forms an elliptic cylindrical shape having linear part, it is
preferable that the length of the above-described pinching plates
be shorter than that of the linear part of said power generating
elements. The reason for this is that the connection is easy and
the reliability is also improved.
[0018] Moreover, when the power generating element forms an
elliptic cylindrical shape, it is desirable that a set of
above-described connecting plate portions be present per power
generating element, that one above-described pinching plate be
present per connecting plate portion, that a set of connecting
plate portions be disposed so as to hold the end portion of the
power generating element from the outside, and that the pinching
plate be disposed so as to lie at the outside of the connecting
plate portion and at the center of the winding of the power
generating element. This allows the efficiency of the connection
work and the reliability of the connection to be improved.
[0019] In addition, it is preferable that a battery case be
equipped with external connection terminals, and that this external
connection terminal be connected to a current-collector connector.
The reason for this is that the external current drawing structure
can be configured easily.
[0020] When a battery case is equipped with external connection
terminals, it is preferable to be equipped with battery terminals,
which are set on the exterior of the battery case, and terminal
connection members, which are disposed on the exterior of the
above-described battery case and connected and fixed to the outward
protruding portion of said battery terminal, and to connect an
external connection terminal through said terminal connection
member.
[0021] The external connection terminal is not only locked on but
also firmly connected and fixed to the terminal connection member;
therefore charging/discharging current can pass through the section
where the external connection terminal comes in contact with a
connection member of an external circuit directly or through a
clamping member and the like as well as the section where the
connection member of the external circuit comes in direct contact
with the terminal connection member; hence, it becomes possible to
reduce the contact resistance at the terminals and improve the
battery performance.
[0022] In addition, when the current-collector connector main
portion forms an approximately trapezoidal shape, it is desirable
that an terminal insertion hole for external connection be formed
at a section near the short side of the approximately trapezoidal
shape of said current-collector connector main portion, that one
end of said external connection terminal be connected and fixed to
said terminal insertion hole for external connection in the inside
of the battery case, and that the other end be derived to the
outside of the battery case. The reason for this is that the volume
efficiency becomes high and the current drawing structure can be
configured easily.
[0023] Moreover, regarding the terminal insertion hole for external
connection, when the distance from the center of the short side of
the approximately trapezoidal shape of said current-collector
connector main portion to the center of said terminal insertion
hole is referred to as D and the diameter of the terminal insertion
hole for external connection is referred to as R, it is preferable
that R be not less than 0.5 D.
[0024] If R is set less than 0.5 D, the intensity in the vicinity
of the terminal insertion hole declines and the vibratility
resistance deteriorates; therefore, failure or bad connection
occurs in this section during the use of the battery, thereby
causing a decrease in battery reliability. If R is set greater than
4 D, a section unnecessary for the current-collection function
increases and this results in an increase in the battery weight;
therefore, it is preferable that R be not greater than 4 D. In
addition, regarding the approximately trapezoidal shape, an
isosceles triangle may be employed as an extreme case; however, if
this is the case, an angular shape having a ridge longer than R is
preferable to a shape having a completely acuminate crest.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is an assembly perspective view showing an embodiment
of the present invention.
[0026] FIG. 2 is a cross-section view showing a state where a
connecting plate portion and an electrode are inserted in a
pinching plate.
[0027] FIG. 3 is a view showing the configuration of a power
generating element.
[0028] FIG. 4 is an assembly perspective view showing an embodiment
of the present invention.
[0029] FIG. 5 is a perspective view showing an embodiment of the
current-collector connector which is used in the present
invention.
[0030] FIG. 6 is an assembly perspective view showing an embodiment
of the present invention.
[0031] FIG. 7 is an assembly perspective view showing an embodiment
of the present invention.
[0032] FIG. 8 is a view showing a prior art example.
PREFERRED EMBODIMENTS OF THE INVENTION
[0033] Hereinafter, embodiments of the present invention will be
described with reference to the accompanying drawings.
[0034] FIG. 1 is an assembly perspective view showing an embodiment
of the present invention, and FIG. 2 is a cross-section view
showing a state where a connecting plate portion and an electrode
are inserted in a pinching plate.
[0035] The embodiment describes a large non-aqueous electrolyte
secondary battery. In this non-aqueous electrolyte secondary
battery, as shown in FIG. 1, two power generating elements 1, 1 of
an elliptic cylindrical shape are aligned and connected in
parallel. Each power generating element 1 has the same
configuration as that of the prior art, where the aluminum foil at
the side-edge portions of a positive electrode 1a protrudes from
one end face of the elliptic cylindrical shape and the copper foil
at the side-edge portions of a negative electrode 1b protrudes from
the other end face.
[0036] The above-described two power generating elements 1, 1 are
aligned horizontally so that the flat sides of each elliptic
cylindrical shape overlap each other in an upright stance. And,
current-collector connecting plates 2, 2 are disposed at both ends
of these two power generating elements 1, 1, respectively. The
current-collector connecting plates 2, 2 are made of metal plates
thick enough to obtain a large current capacity, respectively; a
plate for the positive electrode 1a side to be disposed at one end
of the power generating element 1 is made of an aluminum-alloy
plate, and a plate for the negative electrode 1b side to be
disposed at the other end is made of a copper-alloy plate. Each
current-collector connecting plate 2 consists of a main portion 2a,
which is horizontally disposed and forms an approximately
trapezoidal shape, and four elongated connecting plate portions 2b,
which are provided so as to protrude downward from the base (long
side) of this trapezoidal main portion. In addition, on each
connecting plate portion 2b, convex portions protruding from the
plate face are formed at several points at arbitrary intervals.
That is, each current-collector connecting plate 2 is formed as
follows: a trapezoidal main portion 2a and four elongated
connecting plate portions 2b, which extend straight in a tine shape
from the base of this trapezoidal portion, are punched in an
aluminum-alloy plate or a copper-alloy plate by press work and
convex portions are formed on each connecting plate portion 2b;
these connecting plate portions 2b are folded at the base of them
at a right angle with respect to the main portion 2a; and each
folded connecting plate portion 2b is twisted at 90 degrees at the
base, respectively. In addition, these four connecting plate
portions 2b are coupled into two pairs side by side, and the sides
facing each other in each pair of two connecting plate portions 2b
are twisted so as to turn in the opposite direction with respect to
the main portion 2a. And, due to this twist, the convex portions on
each connecting plate portion 2b are provided so as to protrude in
the direction that a pair is facing each other.
[0037] The length of the twisted portion in the protruding
direction of said each connecting plate portion 2b, L, is set
longer than the thickness of this connecting plate portion 2b, T.
The reason for this is that when the length L is shorter than the
thickness T, precipitous twisting is applied to this connecting
plate portion 2b, stress is concentrated on the twisted portion,
and electronic conductivity deteriorates.
[0038] In the above-described each current-collector connecting
plate 2, the main portion 2a is disposed over both end portions of
the two power generating elements 1, 1, and connecting plate
portions 2b are provided so as to be disposed along the end faces
of these power generating elements 1, 1. That is, at the end face
side of each power generating element 1 from which the aluminum
foil of the positive electrode la protrudes, the current-collector
connecting plate 2 made of an aluminum-alloy plate is disposed, and
at the other end face side from which the copper foil of the
negative electrode 1b protrudes, the current-collector connecting
plate 2 made of a copper-alloy plate is disposed. In addition, a
pair of two connecting plate portions 2b is disposed along both
sides of the metal foil of the positive electrode 1a or the
negative electrode 1b which protrudes from the end face of each
power generating element 1. Here, at both end faces of each power
generating element 1, the metal foil of the positive electrode 1a
or the negative electrode 1b sticks out and protrudes in a wound
state and an elliptic cylindrical shape; therefore, it is possible
to divide the section of the linear part between the bent sides of
the elliptic cylindrical shape, where sheets of such metal foil
vertically overlap each other, into two halves from side to side
with respect to the winding axis. And, the pair of two connecting
plate portions 2b being disposed every end face of each power
generating element 1 is disposed respectively outside the metal
foil overlapping portions being separated from side to side. In
this case, a pair of two connecting plate portions 2b is twisted in
the direction to which the inner sides being originally laid
opposite each other escape from the power generating element 1;
therefore, the metal foil protruding from the end face of each
power generating element 1, especially the upper bent portion, can
naturally fit in between the two connecting plate portions 2b
composing a pair.
[0039] After the current-collector connecting plate 2 is disposed
as above described, the metal foil of the positive electrode 1a and
the negative electrode 1b in the power generating element 1 is
connected and fixed to each connecting plate portion 2b by means of
a pinching plate 4 (FIG. 2.) That is, in each end face of each
power generating element 1, the linearly overlapping portions of
the metal foil are first separated from side to side and put along
the connecting plate portion 2b of the respective sides, and these
connecting plate portion 2b and metal foil are inserted and held in
the pinching plate 4. Accordingly, to the inside faces of the two
connecting plate portions 2b composing a pair, the metal foil
overlapping portions being divided into halves from side to side
are closely appressed. And, ultrasonic welding is performed from
both sides of each pinching plate 4 where the connecting plate
portion 2b and the metal foil are held as above described, thereby
allowing these connecting plate portion 2b and metal foil of the
positive electrode 1a or the negative electrode 1b to be joined.
Each pinching plate 4 is provided by folding a strip of relatively
thin metal plate into two at the center along a long side; the
pinching plate 4 made of the aluminum-alloy plate is used for the
positive electrode 1a side, and the pinching plate 4 made of the
copper-alloy plate is used for the negative electrode 1b side.
These pinching plates 4 are used only for the welding and the firm
connection and fixing of the connecting plate portion 2b and the
metal foil; therefore, a large current capacity is not necessary in
particular, and a metal plate having an adequate thickness to allow
optimal ultrasonic welding can be used. In each connecting plate
portion 2b, in addition, the convex portions 2b1 are formed on the
inside face which overlaps with the metal foil; therefore, such
metal foil can receive ultrasonic energy at each convex portion in
a centralized manner, thereby allowing the welding to be performed
surely.
[0040] In the above-described pinching plates 4, the length should
be shorter than that of the linear part in the cylindrical shape of
the metal foil of the positive electrode 1a or the negative
electrode 1b protruding from the end face of the power generating
element 1. This allows the pinching plates 4 to hold only the
linear part of the metal foil together with the connecting plate
portion 2b. The reason for this is that if the length of the
pinching plate 4 is longer than that of the linear part of the
metal foil, the pinching plate 4 would hold the upper and lower
bent sides of the cylindrically protruding metal foil, thereby
causing a fear that these portions of the metal foil are forcedly
pulled toward the pinching plate 4 and damaged.
[0041] Positive and negative electrode terminals 3, 3 of a
non-aqueous electrolyte secondary battery of the present embodiment
are respectively configured with a rivet terminal (an external
connection terminal) 3a, a terminal connection rod (a terminal
connection member) 3b, and a terminal bolt (a battery terminal) 3c.
The rivet terminal 3a is provided in such a manner that a
cylindrical caulking portion protrudes from the upper and lower
faces of a square flange with four chamfered corners, made of
aluminum or aluminum alloy if the terminal 3 is used for the
positive terminal, and made of copper or copper alloy if the
terminal 3 is used for the negative terminal. In this rivet
terminal 3a, the caulking portion in the lower part comes in
contact with an electrolyte solution; therefore, in case of a
non-aqueous electrolyte secondary battery, for the positive
terminal side it is necessary to use the aluminum, aluminum alloy
or the like which does not dissolve in a non-aqueous electrolyte
solution, and for the negative terminal side it is necessary to use
the copper, copper alloy or the like which does not alloy with a
negative active material. The terminal connection rod 3b is made of
a copper-alloy metal plate of a rectangular shape, at both ends of
which through-holes are made. In addition, the terminal bolt 3c is
a stainless steel hexagon bolt, where a bolt portion is provided so
as to upwardly protrude from the upper face of the hexagonal head
portion. These terminal connection rod 3b and terminal bolt 3c do
not come in contact with an electrolyte solution; therefore, for
use as the terminal connection rod 3b, copper alloy having high
electric conductivity and sufficient mechanical strength is used in
particular and, for use as the terminal bolt 3c to be connected
with the external circuit, stainless steel having high mechanical
strength and sufficient electric conductivity is used in
particular.
[0042] The main portions 2a, 2a of the above-described
current-collector connectors 2, 2 are disposed, practically before
being attached to the power generating elements 1, 1, at both end
portions of the undersurface of a cover plate 6 with lower
insulating sealants 5, 5 therebetween, respectively, as shown in
FIG. 4. In addition, at both end portions of the top surface of the
cover plate 6, rivet terminals 3a, 3a, terminal connection rods 3b,
3b, and terminal bolts 3c, 3c are disposed with upper insulating
sealants 7, 7 therebetween, respectively. In each rivet terminal
3a, however, the tip of the caulking portion in the lower part is
fitted in a through-hole (a terminal insertion hole) being provided
in the main portion 2a of the current-collector connector 2 via the
through-holes being provided in the lower insulating sealant 5, the
cover plate 6 and the upper insulating sealant 7, and connected and
fitted by caulking. Then, the rivet terminal 3a is isolated from
the cover plate 6 by means of the insulating sealants 5, 7. In
addition, when the caulking portion in the lower part of the rivet
terminal 3a and the main portion 2a of the current-collector
connector 2 are caulked, the insulating sealants 5, 7 come to hold
and press the cover plate 6; hence, the through-hole on this cover
plate 6 is sealed. In each terminal connection rod 3b disposed at
both end portions of the top surface of the cover plate 6 with the
upper insulating sealants 7, 7 therebetween, respectively, the
caulking portion in the upper part of the rivet terminal 3a is
fitted in one through-hole from the underneath and connected and
fitted by caulking, and the bolt portion of the terminal bolt 3c is
fitted in the other through-hole from the underneath. Then, a
hexagonal head portion of the terminal bolt 3c is fitted in a
hexagonal concave portion of the upper insulating sealant 7,
thereby prevented from slewing. In this terminal bolt 3c, by
leaving the bolt portion fitted and locked in the through-hole of
the terminal connection rod 3b, it is possible to make the bolt
portion be connected and fitted to the terminal connection rod 3b
only when an external-circuit connection member is put on this bolt
portion and fastened by a nut, or it is possible to connect and fit
the head portion or the like in advance to the terminal connection
rod 3b by welding or the like. As described above, when the
terminal bolt 3c is connected and fitted in advance to the terminal
connection rod 3b, even if the external-circuit connection member
is not fastened tightly by the nut, current flows steadily from
this terminal connection rod 3b to the area where the nut comes in
contact with the connection member through the terminal bolt 3c, as
well as the area where the terminal connection rod 3b comes in
direct contact with the connection member, so that the contact
resistance with the terminal 3 and the connection member can be
reduced.
[0043] As described above, the terminals 3, 3 are disposed at both
end portions of the top surface of the cover plate 6, and the
current-collector connectors 2, 2 are mounted at both end portions
of the undersurface of the cover plate 6, and then, as described
above, the power generating elements 1, 1 are connected to these
current-collector connectors 2, 2. And, these two power generating
elements 1 are housed inside a stainless steel battery case 8 of an
enclosure type, and the upper opening of this battery case 8 is
covered with the cover plate 6. And, the circumference of the cover
plate 6 is sealed by welding, the inside of the battery case 8 is
filled with an electrolyte solution, and this inside is sealed
hermetically, thereby producing a non-aqueous electrolyte secondary
battery. In the non-aqueous electrolyte secondary battery, two
power generating elements 1 are housed in a horizontal arrangement
so that the flat side faces of the elliptic cylindrical shape are
in an upright position, and the terminal bolts 3c of the terminals
3 protrude from both end portions of the top surface of the cover
plate 6; therefore, the efficiency of installation space becomes
satisfactory.
[0044] According to the non-aqueous electrolyte secondary battery
configured as above described, the positive electrode 1a or the
negative electrode 1b of each power generating element 1 and the
terminal 3 are connected through the main portion 2a and connecting
plate portions 2b of the current-collector connector 2 having a
large current capacity; therefore, it becomes possible to flow
sufficiently large charging/discharging current. Furthermore, the
metal foil of the positive electrode 1a or the negative electrode
1b of each power generating element 1 is connected to the
connecting plate portion 2b by ultrasonic welding through the
pinching plate 4 consisting of a somewhat thin metal plate;
therefore, the welding is performed adequately so that the metal
foil does not peel off easily.
[0045] In addition, the main portion 2a of the current-collector
connector 2 is displaced horizontally over the two power generating
elements 1, 1, thereby making the connection with the terminal 3
through the cover plate easy, and the connecting plate portion 2b
is folded downward, twisted, and protruded from this main portion
2a, thereby allowing the face of this connecting plate portion 2b
to be set along the vertical metal foil of the positive electrode
1a or the negative electrode 1b protruding from the end face of
each power generating element 1; therefore, the connection with the
metal foil becomes easy. That is, with not being twisted, each
connecting plate portion 2b lies in a direction perpendicular to
the metal foil, and this makes the connection not easy. In
addition, when the connecting plate portion 2b of the
current-collector connector 2 is formed by folding down a plate
which protrudes toward both sides along the alignment direction of
the power generating elements 1, 1 with respect to the main portion
2a, the face of the connecting plate portion 2b can be set along
the metal foil protruding from the end face of the power generating
element 1, though only one connecting plate portion 2b can be
allocated to each power generating element 1, so that in case of a
battery where three or more power generating elements 1 are
disposed side by side, it becomes impossible to perform current
collection from the one or more power generating elements 1
locating in the middle. Furthermore, the current-collector
connector 2 of the present embodiment can be produced only by
providing simple processes of punching, folding, and twisting in
one sheet of metal plate.
[0046] In addition, a pair of two connecting plate portions 2b is
disposed per end face of each power generating element 1;
therefore, even if the width of the connecting plate portions 2b is
made narrower, sufficient current capacity can be attained, and the
amount of the metal foil protruding from this end face can be
reduced. Furthermore, the metal foil protruding from each end face
of each power generating element 1 is inserted between the pair of
two connecting plate portions 2b along their twisting direction;
therefore, the assembly work becomes easy.
[0047] In the above-described embodiment, ultrasonic welding was
mentioned as the means of connecting the connecting plate portion
2b and the metal foil of the positive electrode 1a or the negative
electrode 1b into the pinching plate 4; however, welding can be
performed using other welding methods such as spot welding or the
like. In addition, instead of performing such welding, by applying
firm pressure on the pinching plate 4 from the outside, the
connecting plate portion 2b and the metal foil can be crimped. In
this case, unlike in the case of welding, it is necessary to use a
somewhat thick metal plate for the pinching plate 4 so that the
power generating element connection portion 2a and the metal foil
can be firmly crimped and supported.
[0048] Moreover, to the connecting plate portion 2b, even if convex
portions are not formed on it, the metal foil can be firmly welded
or crimped. In addition, in the above-described embodiment, the
pinching plate 4 was mentioned as being used for connecting the
connecting plate portion 2b and the metal foil of the positive
electrode 1a or the negative electrode 1b; however, it is possible
to make connection by using connecting parts other than the
pinching plate 4 or by using none of the connecting parts.
[0049] In addition, in the above-described embodiment, the
non-aqueous electrolyte secondary battery was mentioned as being
configured by disposing two power generating elements 1, 1 side by
side; however, the number of the power generating elements 1 is not
limited; hence, any number, one or more, of power generating
elements 1 can be used in the battery, and the battery is not to be
considered limited to a non-aqueous electrolyte secondary battery,
either. Moreover, in the above-described embodiment, a pair of two
connecting plate portions 2b of the current-collector connector 2
was mentioned as being disposed per positive or negative electrode
of each power generating element 1, respectively; however, at least
one or more connecting plate portions 2b can be disposed at the
positive or negative electrode of each power generating element 1,
respectively.
[0050] In addition, in the above-described embodiment, the terminal
3 was mentioned as being configured with the rivet terminal 3a, the
terminal connection rod 3b, and the terminal bolt 3c; however, the
configuration of the terminal 3 is not limited specifically; hence,
it can be configured with a single part such as shown in FIG.
9.
[0051] In addition, in the above-described embodiment, the wound
type power generating element 1 of an elliptic cylindrical shape
was explained; however, even in case a laminated type power
generating element 1 is used, the metal foil of the positive
electrode 1a or the negative electrode 1b protruding from the end
face of the lamination layers can be connected and fixed in the
same manner. Moreover, in the above-described embodiment, the
battery exterior consisting of the battery case 8 and the cover
plate 6 was exemplified; however, the configuration of the battery
exterior is not limited specifically. In addition, in the
above-described embodiment, the non-aqueous electrolyte secondary
battery was explained; however, the type of the battery is not
limited specifically, either.
[0052] FIG. 5 is a perspective view showing an embodiment of the
current-collector connector which is used in the present invention,
FIG. 6 is an assembly perspective view showing an embodiment of the
present invention, and FIG. 7 is an assembly perspective view
showing a battery structure which employs the power generating
element 1 and the current-collector connector 2 shown in FIG.
6.
[0053] In this non-aqueous electrolyte secondary battery, as shown
in FIG. 6, four of the power generating element 1 of an elliptic
cylindrical shape are closely aligned and connected in parallel. In
each power generating element 1, the aluminum foil at the side-edge
portions of a positive electrode 1a protrudes from one end face of
the elliptic cylindrical shape, and the copper foil at the
side-edge portions of a negative electrode 1b protrudes from the
other end face.
[0054] The above-described four power generating elements 1 are
aligned closely so that the flat sides of each elliptic cylindrical
shape come in contact with each other, and the connecting plate
portions 2b of current-collector connecting plates 2 are disposed
respectively at both end faces of these power generating elements
1. Regarding the current-collector connecting plates 2, the one to
be disposed at one end face of the power generating elements 1 is
made of an aluminum-alloy plate, and the one to be disposed at the
other end face is made of a copper-alloy plate. In addition, for
these current-collector connecting plates 2, somewhat thick metal
plates are used so that large current during high rate discharge
can flow sufficiently. In this example, a thickness of 1.7 mm is
used for either plate.
[0055] The main portions 2a of these current-collector connectors
are horizontally-disposed metal plates which form a rather flat,
approximately isosceles triangular shape (in the present
application, this shape is considered included in an approximately
trapezoidal shape), and eight elongated connecting plate portions
2b are provided so as to protrude downward from the base of this
triangular shape. These connecting plate portions 2b are formed in
such a manner that elongated metal plates are punched in a metal
plate for the current-collection connection 2 by press work, and
that the obtained portions are folded downward and twisted at 90
degrees. In addition, as shown in FIG. 2, several protruding convex
portions 2b1 are formed on one surface of the metal plate.
[0056] The above-described current-collector connectors 2 are
provided so as to be disposed over both end portions of the four
power generating elements 1, respectively, and the connecting plate
portions 2b are provided so as to be disposed along the end faces
of these power generating elements 1. At the end face side of the
power generating elements 1 from which the aluminum foil of the
positive electrode la protrudes, the current-collector connecting
plates 2 made of an aluminum-alloy plate are disposed, and at the
end face side from which the copper foil of the negative electrode
1b protrudes, the current-collector connecting plates 2 made of a
copper-alloy plate are disposed. In addition, two connecting plate
portions 2b are disposed at every end face of each power generating
element 1.
[0057] Here, at the end face of each power generating element 1,
the aluminum foil of the positive electrode 1a or the copper foil
of the negative electrode 1b sticks out in a wound state and an
elliptic cylindrical shape; therefore, the section where such metal
foil vertically aligns in bundle is divided from side to side with
respect to the winding axis. And, the two connecting plate portions
2b being disposed every power generating element 1 are disposed
respectively outside the bundle of the metal foil which are
separated from side to side. In addition, as shown in FIG. 2, these
two connecting plate portions 2b are twisted at 90 degrees in an
opposite direction from each other so that the face of the
protruding side of the convex portion 2b1 can face inside, or the
side of the metal foil bundle.
[0058] After the connecting plate portions 2b of the
current-collector connector 2 are disposed as above described, the
bundle of the metal foil of the positive electrode 1a or the
negative electrode 1b is held together with the connecting plate
portion 2b by means of a pinching plate 4. The pinching plate 4 is
provided by folding a strip of metal plate into two along a long
side; the aluminum-alloy plate is used for the connecting plate
portions 2a of the positive electrode 1a side, and the copper-alloy
plate is used for the connecting plate portions 2b of the negative
electrode 1b side.
[0059] And, ultrasonic welding is performed from both sides of
these pinching plates 4; hence, the connecting plate portion 2b of
the current-collector connector 2 and the bundle of the metal foil
of the positive electrode 1a or the negative electrode 1b, which
are held in the respective pinching plates 4, are welded.
[0060] The parts of an approximately isosceles triangular shape of
the positive and negative current-collector connectors 2 which are
disposed over both ends of the power generating elements 1, as
shown in FIG. 7, are mounted at both sides of the undersurface of a
rectangular cover plate 6 with the insulating sealants 5
therebetween. The cover plate 6 is made of a stainless steel plate,
at both sides of whose top surface the positive and negative
terminals 3 are disposed with other insulating sealants 7
therebetween. Regarding these terminals 3a, the lower end portion
is passed through the cover plate 6 into a terminal insertion hole
10 being provided near the vertex of the approximately isosceles
triangular shape of the respective current-collector connectors 2,
and connected and fixed by caulking.
[0061] In addition, the upper end portion of these terminals 3a is
connected and fixed by caulking to a connection conductor 3b which
locks an external terminal 3C being disposed on the insulating
sealant 7. Regarding these terminals 3a, the one which is made of
aluminum-alloy is used for the current-collector connector 2 of an
aluminum-alloy plate, and the one which is made of copper-alloy is
used for the current-collector connector 2 of a copper-alloy
plate.
[0062] However, the connection conductors 3b and the external
terminals 3c do not come in contact with an electrolyte solution;
therefore, steel alloy, iron alloy or the like, the strength of
which is higher than that of aluminum alloy, copper alloy or the
like, is used. The insulating sealants 5, 7, which are disposed on
the top and the back of the cover plate 6, are the resin molding
plates which isolate and seal the cover plate 6 from the
current-collector connectors 2, and the terminals 3a (corresponding
to external connection terminals), the connection conductors 3b
(corresponding to terminal connection members) and the external
terminals 3C (corresponding to battery terminals) 3C.
[0063] Above-described four power generating elements 1 are housed
in a battery case body, which is not illustrated, and the cover
plate 6 is fitted in an upper end opening of this battery case body
and firmly fixed by welding or the like. And, the inside of this
battery case body is filled with an electrolyte solution, thereby
producing a non-aqueous electrolyte secondary battery.
[0064] According to the above-described battery structure, the
terminal 3a made of aluminum alloy or copper alloy is connected and
fixed to the connection conductor 3b made of steel alloy, iron
alloy or the like, and the connection with an external circuit is
made through the external terminal 3C being locked with this
connection conductor 3b; therefore, there is no need to directly
cramp the terminal 3a made of low-strength aluminum alloy or copper
alloy with a screw, and no fear of damaging the terminal 3a by
fastening this screw cramp or deforming the terminal 3a due to
vibration or shock.
[0065] In addition, in the above-described embodiment, the metal
foil of the positive electrode 1a or the negative electrode 1b was
explained as being disposed only at the one side of the connecting
plate portion 2b; however, the metal foil may be disposed at both
sides so that both sides can be held in the pinching plate 4.
Moreover, in the above-described embodiment, two connecting plate
portions 2b were disposed at one end face of each power generating
element 1; however, the number of this connecting plate portions 2b
to be disposed is not limited. For example, one power-generation
connecting plate portion 2b may be disposed per end face of each
power generating element 1, or the metal foil protruding from the
end faces of the two power generating elements 1 lying next to each
other can be welded or crimped together to this one connecting
plate portion 2b.
[0066] The current-collector connectors 2 used in the battery such
as shown in FIG. 6 were formed by cutting and removing the
triangular edges 2c of both sides of the terminal insertion hole 10
of the current-collector connector 2 such as shown in FIG. 5;
however, it is possible to use them without cutting both sides.
However, in the comparison of the batteries employing those with
these two shapes, although no difference is noted in their current
collection efficiencies, the battery shown in FIG. 6 is found to be
lighter in weight and higher in weight energy density.
[0067] In the above-described embodiment, a non-aqueous electrolyte
secondary battery was explained; however, any type of battery may
be used. For reference's sake, the basic configuration of the
non-aqueous electrolyte secondary battery in the present invention
can be exemplified as follow.
[0068] First, as a positive active material, various materials can
be used including titanium dioxides, lithium-cobalt composite
oxides, spinel-type lithium manganese oxides, vanadium pentoxides,
and molybdenum trioxides; among them, lithium-cobalt composite
oxides (LiCoO.sub.2) and spinel-type lithium manganese oxides
(Li.sub.xMn.sub.2O.sub.4) are capable of performing
charge/discharge with an extremely electropositive potential not
less than 4 V (4Li/Li.sup.+); hence a battery having a high
discharge voltage can be provided by using these as a positive
electrode.
[0069] Regarding a positive electrode, aluminum foil having a
thickness of 10 to 30 .mu.m is common as a current collector,
typically both sides of said current collector are coated with an
active material layer, and it is preferable that the active
material layer be 50 to 150 .mu.m (per one face) in thickness, 1.8
to 3.0 g/cc in density, and 25 to 45% in porosity in terms of life
performance and charge/discharge characteristics.
[0070] To a negative electrode, various materials can be applied
including lithium metal, Li-Ai alloys capable of undergoing
absorption/desorption of lithium, or carbon materials; among them,
carbon materials have the advantage of allowing a battery to have
high safety and long cycle life.
[0071] In this case, copper foil having a thickness of 10 to 20
.mu.m is suitable as a current collector, and it is preferable that
the active material layer be 45 to 125 .mu.m (per one face) in
thickness, 1.15 to 2.5 g/cc in density, and 25 to 45% in porosity
in terms of life performance and charge/discharge
characteristics.
[0072] In addition, an electrolyte solution is prepared as follows:
a solvent of low viscosity such as 1,2-dimethoxyethane, dimethyl
carbonate, ethyl methyl carbonate or diethyl carbonate is mixed
into a solvent of high conductivity such as propylene carbonate,
ethylene carbonate, 7-butyrolactone or sulfolane, and then lithium
perchlorate, lithium trifluoromethan sulfate or lithium
hexafluorophosphate is added as a solute to this mixture. Instead
of using such liquids, it is possible to use the electrolytes of
all solid state or gel electrolytes, or these electrolytes in
combination with liquid electrolytes.
[0073] An electrode can be produced by coating metal foil with the
slurry which is prepared by mixing, for example, an active
material, a binder, and a solvent. For use as a binder,
fluorocarbon resins such as poly(vinylidene fluoride) and
poly(tetrafluoroethylene) are superior in oxidation-reduction
resistance and electrolyte solution resistance; among them,
poly(vinylidene fluoride) soluble in organic solvent is most widely
used at present because it allows easy preparation of slurry. The
preferable amount is 2 to 6 wt. % for use in a positive electrode,
and 6 to 10 wt. % for use in a negative electrode.
[0074] For use as a separator, a porous resin film having a
thickness of 20 to 60 .mu.m is preferable; however, polymer
electrolyte membrane can also be used.
INDUSTRIAL APPLICABILITY
[0075] According to the battery of the present invention, even when
power generating elements and terminals are disposed in
consideration of space efficiency, by the use of a
current-collector connecting plate of a simply processed metal
plate, it becomes possible to perform current collection
efficiently. Furthermore, it becomes possible to make secure the
connection between the electrodes in the power generating elements
and the connecting plate portions of the current-collector
connecting plates, and possible to perform the assembly work
easily.
* * * * *